Self-awareness in humans is more complex, diffuse than previously thought

August 22, 2012

Researchers at the University of Iowa studied the brain of a patient with rare, severe damage to three regions long considered integral to self-awareness in humans (from left to right: the insular cortex, anterior cingulate cortex, and the medial prefrontal cortex). Based on the scans, the UI team believes self-awareness is a product of a diffuse patchwork of pathways in the brain rather than confined to specific areas. Credit: Department of Neurology, University of Iowa

Ancient Greek philosophers considered the ability to "know thyself" as the pinnacle of humanity. Now, thousands of years later, neuroscientists are trying to decipher precisely how the human brain constructs our sense of self.

Self-awareness is defined as being aware of oneself, including one's traits, feelings, and behaviors. Neuroscientists have believed that three brain regions are critical for self-awareness: the insular cortex, the anterior cingulate cortex, and the medial prefrontal cortex. However, a research team led by the University of Iowa has challenged this theory by showing that self-awareness is more a product of a diffuse patchwork of pathways in the brain – including other regions – rather than confined to specific areas.

The conclusions came from a rare opportunity to study a person with extensive brain damage to the three regions believed critical for self-awareness. The person, a 57-year-old, college-educated man known as "Patient R," passed all standard tests of self-awareness. He also displayed repeated self-recognition, both when looking in the mirror and when identifying himself in unaltered photographs taken during all periods of his life.

"What this research clearly shows is that self-awareness corresponds to a brain process that cannot be localized to a single region of the brain," said David Rudrauf, co-corresponding author of the paper, published online Aug. 22 in the journal PLOS ONE. "In all likelihood, self-awareness emerges from much more distributed interactions among networks of brain regions." The authors believe the brainstem, thalamus, and posteromedial cortices play roles in self-awareness, as has been theorized.

The researchers observed that Patient R's behaviors and communication often reflected depth and self-insight. First author Carissa Philippi, who earned her doctorate in neuroscience at the UI in 2011, conducted a detailed self-awareness interview with Patient R and said he had a deep capacity for introspection, one of humans' most evolved features of self-awareness.

"During the interview, I asked him how he would describe himself to somebody," said Philippi, now a postdoctoral research scholar at the University of Wisconsin-Madison. "He said, 'I am just a normal person with a bad memory.'"

Patient R also demonstrated self-agency, meaning the ability to perceive that an action is the consequence of one's own intention. When rating himself on personality measures collected over the course of a year, Patient R showed a stable ability to think about and perceive himself. However, his brain damage also affected his temporal lobes, causing severe amnesia that has disrupted his ability to update new memories into his "autobiographical self." Beyond this disruption, all other features of R's self-awareness remained fundamentally intact.

"Most people who meet R for the first time have no idea that anything is wrong with him," noted Rudrauf, a former assistant professor of neurology at the UI and now a research scientist at the INSERM Laboratory of Functional Imaging in France. "They see a normal-looking middle-aged man who walks, talks, listens, and acts no differently than the average person."

"According to previous research, this man should be a zombie," he added. "But as we have shown, he is certainly not one. Once you've had the chance to meet him, you immediately recognize that he is self-aware."

Patient R is a member of the UI's world-renowned Iowa Neurological Patient Registry, which was established in 1982 and has more than 500 active members with various forms of damage to one or more regions in the brain.

The researchers had begun questioning the insular cortex's role in self-awareness in a 2009 study that showed that Patient R was able to feel his own heartbeat, a process termed "interoceptive awareness."

The UI researchers estimate that Patient R has ten percent of tissue remaining in his insula and one percent of tissue remaining in his anterior cingulate cortex. Some had seized upon the presence of tissue to question whether those regions were in fact being used for self-awareness. But neuroimaging results presented in the current study reveal that Patient R's remaining tissue is highly abnormal and largely disconnected from the rest of the brain.

"Here, we have a patient who is missing all the areas in the brain that are typically thought to be needed for self-awareness yet he remains self-aware," added co-corresponding author Justin Feinstein, who earned his doctorate at the UI in February. "Clearly, neuroscience is only beginning to understand how the human brain can generate a phenomenon as complex as self-awareness."

(Medical Xpress) -- Consciousness is a selective process that allows only a part of the sensory input to reach awareness. But up to today it has yet to be clarified which areas of the brain are responsible for the content ...

Brain damage can cause significant changes in behaviour, such as loss of cognitive skills, but also reveals much about how the nervous system deals with consciousness. New findings reported in the July 2011 issue of Elsevier's ...

Recommended for you

Researchers at the University of Pittsburgh have uncovered the mechanism by which neurons keep up with the demands of repeatedly sending signals to other neurons. The new findings, made in fruit flies and mice, challenge ...

When we have a new experience, the memory of that event is stored in a neural circuit that connects several parts of the hippocampus and other brain structures. Each cluster of neurons may store different aspects of the memory, ...

Researchers at the University of California, Riverside have devised a method to selectively erase particular fear memories by weakening the connections between the nerve cells (neurons) involved in forming these memories.

The human brain has a region of cells responsible for linking sensory cues to actions and behaviors and cataloging the link as a memory. Cells that form these links have been deemed highly stable and fixed.

Researchers from the National Institutes of Health have identified a class of sensory neurons (nerve cells that electrically send and receive messages between the body and brain) that can be activated by stimuli as precise ...

Itching is an unpleasant sensation associated with the desire to scratch, and the itch sensation is an important protective mechanism for animals. However, chronic itch, often seen in patients with skin and liver diseases, ...

17 comments

Let me break it down for you:A: Animals thoughts are driven uniquely by needB: Our brains are social machines which involves most of the brainC: Existencial awareness is derived from the capability to sense painD: All other awareness beginning with identity are all derived from complete language (not just commands or queues like dolphins) E: Awareness can also be derived from dreamsF: All humans are garanteed awareness, short of a brain.G: The need for advanced language is what developed are human intellegenceH: Our imaginative capabilities are unparalleled since we are information processors (manipulate) advanced mech. behind that.

If kevinrts was here he would immediately point out the existence of the soul as the source of self-awareness, thereby solving the entire mystery

yup, plus how its so obvious that this must be proof of a maker, no way it could evolve naturally......I'm kind of surprised zephyer isnt here claiming this somehow proves his aether theories somehow. lol

But seriously, is it possible that awareness is in both parts and complete? That is, any part of the brain (or at least, any number of parts) may be capable of sustaining self-awareness, but it is more practical to be departmentalised and parts are prioritised, much how (at least a few species of) octopuses have completely flexible limbs but still choose to bend with artificial "joints"? If they injured where they might put a kink, they can put a kink further up the limb. Likewise, it's more practical to departmentalise for the sake of organisation. Self-awareness isn't restricted to the parts originally believed to be responsible, they're just the DNA's first choice.

Let me break it down further for you.To simplify things, let's just say that awareness is existential awareness. The moment one can sense pain i.e., in a womb they are aware. Language on the hand is what allows for a greater sense of self (to distinguish from peers, physically and in mind).I never said it was restricted to certain parts of the brain. I just said that the majority of it was involved, but that was for my broader definition of awareness. For the new one, it would put constraints (everything involved in processing pain). But language and what allows us to acquire it, play an important role in identity which one can construe as awareness.

Other than the soul, perhaps, self awareness also extends to other parts of the body besides the brain. For example, in TCM, the heart and it's meridian are the seat of passionate emotions. Emotions are an integral part of our self awareness.

Is everyone using the same definition self-awareness? Clearly it's not in these three parts - in this case, may be he was able to relocate the relevant functions as the essential parts failed? Or you could recalibrate the tests until he fails and others pass.

I would say self-awareness derives from the internal simulation mechanism (which I'd guess is powered by the same mechanisms as imagination and dreaming and so on) that is our sole experience of the world. No one actually experiences reality directly, obviously, since that's not how the biological systems work. This is also what buddhism and such seems to be trying to teach you.

To put it simply, all of the nerves collect data points, sends them off to the brain, which turns them into the experience of experiencing via the internal representation of the world.

Or as wikipedia puts it, for vision: "An image is produced by the patterned excitation of the cones and rods in the retina. The excitation is processed by the neuronal system and various parts of the brain working in parallel to form a representation of the external environment in the brain"

What you see out of your eye is not actually outside.

As for eric96, all beasts feel pain, even some plants.. So that's pretty irrelevan

Sorry you just blundered a bunch of false statements.1. Plants do not feel pain. They do not possess a nervous system which means necessarily that they cannot perceive pain so despite your obvious compassion for them this is incorrect.

Yes, all animals that have a nervous system and feel pain. Their self-awareness is limited to "I exist". Any greater sense of identity is manifested/enabled by complete language (large vocabulary, grammar and so on and so forth). No animal has this which is why are sense of self is that much more developed.